FR2761173A1 - PROGRAMMABLE PLC MODULE - Google Patents

Abstract

The present invention relates to a programmable logic controller module communicating by serial or parallel link with the central unit and characterized in that it comprises a safety unit (2) made of wired components receiving more than one DC power supply via a series of contacts (S4 to S7) and zero volts via a series of contacts (S0 to S3) and controlling safety relays (K1 and K2) connected to outputs (A3, O1, O2) to which are connected electrical devices (K3, K4) arranged on the power lines and means (L0-7) for reading the state of the various contacts and the state of the outputs associated with the relays.

Description

The present invention relates to an emergency stop monitoring module

  communicating by serial or parallel link with the central unit of a programmable controller. Production workshops and technical installations in buildings are subject to increasing safety requirements. To control, from a protection device (emergency stop), a contactor controlling the power supply of a machine, a security module is used to ensure reliable intermediate relaying by eliminating the risks of a fault in the control circuit (inputs), a fault in the power circuit

  (outputs) or a fault in an internal component of the security module.

  When you want to use such a security module with a PLC

  programmable, the safety module remains independent of the programmable controller.

  The object of the present invention is to provide a monitoring module for a programmable logic controller provided with a safety function in wired logic. The states of the external sensors participating in the safety function and of the commands for the outputs of the wired safety function are read by the processing unit of the PLC. Failures of the system for reading the inputs and outputs of the safety function or the malfunction of the PLC, including its setting

  when de-energized, do not prevent the execution of the module's safety functions.

  The module according to the invention is characterized by the fact that it comprises a safety block made of wired components receiving the most of a continuous supply via a series of contacts and zero volts via a series of contacts and controlling relays of safety connected to outputs to which electrical devices on the power lines are connected and means for reading the status of

  different contacts and the state of the outputs associated with the relays.

  According to one characteristic, the module includes reading blocks made of discrete components, wired in parallel on the input contacts and intended for

PLC diagnosis.

  According to one characteristic, the module includes a reading block carrying out the

  reading of the status of the safety relay control.

  The invention will now be described in more detail with reference to an embodiment given by way of example and represented by the appended drawings in which: - Figure 1 is a diagram of the module according to the invention; - Figure 2 is a functional diagram illustrating the operation of the module. The module marked 1 as a whole is mounted in a programmable controller compartment. It includes an external power supply, a safety block 2 made of wired components, LO to L9 read blocks made of discrete components and intended for PLC diagnostics, a block 4 of interface and isolation

galvanic with the PLC bus.

  An external supply line L1-L2 is connected via terminals A1 and A2 to reading blocks L0 to L9 and via inputs "contacts" and terminals 17 and 13

to safety block 2.

  The "plus" of the DC voltage is applied to a terminal 17 through the series of emergency stop buttons S4 to S7. The "zero v" of the voltage is applied to a terminal 13 via a series of "0" opening contacts or position switches

SO to S3.

  The read blocks L0 to L7 are connected to terminals 10 to 17 so as to be wired in parallel on the input contacts SO to S7. They perform independent reading of each contact. The wiring of the read blocks depends on the number

  and the type of input (single or double contact) to be diagnosed.

  Terminals 13 and 17 are connected to safety block 2 which includes safety relays K1 and K2. The contacts of these relays control the closing and opening of the circuits between safety terminals A3 and 01 on the one hand and A3 and 02

  on the other hand. Safety terminals A3, 01 and 02 are devoid of potential.

  A reading block L9 reads the state of the relay control

K1 and K2.

  A read block L8 reads the state of the validation input.

  Safety block 2 receives the signal from a validation input S8 which is in series with contacts of contactors K3 and K4 so that when this

  input is validated the safety relays K1 and K2 are controlled.

  Interface block 4 interfaces the reading blocks L0 to L9 with the bus

  PLC ensuring galvanic isolation.

  To guarantee the safety function regardless of the first failure, it is mandatory to use emergency stop push buttons or inputs

  position switches with double contacts.

  The operation of the module will now be described.

  After resetting the emergency stop buttons S4 to S7 or closing the position switches SO to S3, a pulse on the validation input S8 supplies the safety relays K1 and K2 and causes the closing of the two circuits of safety outputs A3-01 and A3-02. Contacts K1 and K2 of the safety outputs

  (terminals A3-01 and A3-02) are then closed.

  The module allows the reading of the state of the pushbuttons or position switches of the emergency stop series, the feedback loop and the control of the output circuits. This information is transmitted to the central unit of

  the programmable controller as input bits.

  Pressing one of the emergency stop buttons S4 to S7 or cutting off the external power supply directly opens K1 and K2 and therefore opens the safety output circuits. Opening of SO to S3 contacts

  also causes the opening of the two safety circuits.

  It is understood that it is possible without departing from the scope of the invention to imagine variants and improvements of detail and even to envisage the use

equivalent means.

Claims (7)

  1. Programmable controller module communicating via serial or parallel link with the central unit, characterized in that it comprises a safety block (2) made of wired components receiving most of a continuous supply via a series of contacts (S4 to S7) and zero volts via a series of contacts (SO to S3) and controlling safety relays (K1 and K2) connected to outputs (A3, 01, 02) to which electrical devices are connected ( K3, K4) arranged on the power lines and means (L0-7) to read the state of the various contacts and the state of the outputs associated with relays.   2. Module according to claim 1, characterized in that it comprises reading blocks (L0 to L7) made of discrete components, wired in parallel on the   input contacts (SO to S7) intended for PLC diagnostics.   3. Module according to any one of the preceding claims,   characterized by the fact that it comprises a reading block (L9) carrying out the reading of the state   of the safety relay control (K1 and K2).   4. Module according to any one of the preceding claims,   characterized by the fact that it includes an interface and galvanic isolation block (4) with the PLC bus (5).   5. Module according to any one of the preceding claims,   characterized by the fact that it includes external supply terminals (A1, A2) for   reading blocks for contact inputs (S1 to S7).   6. Module according to any one of the preceding claims,   characterized by the fact that the safety block (2) is connected to a validation input (S8).   7. Module according to any one of the preceding claims,   characterized by the fact that it comprises a reading block (L8) carrying out the reading of the state   of the safety relay control (K1 and K2).